Thailand's military stepped up its propaganda effort and appointed hawkish generals to key advisory roles, tightening its grip on power as it tries to steer the economy away from the brink of recession.

The junta restricted traditional media after it seized power in a coup d'état last week, but fears of a broader media clampdown were heightened Wednesday when most Thai users experienced a 90-minute outage of Facebook. Military officials said the site was only down because of a technical problem, and that it would target...